To electronically control a control equipment or a control system of various industrial machineries, generally a power source, a control equipment, or a detection sensor is electrically connected to an electronic control unit through a cable. For example, the electric power steering system for an automobile is configured so that, a turning direction and a turning torque of a steering shaft that turns by a driver's operation of a steering wheel are detected, and on the basis of these detection values the electric motor is driven so as to rotate in the same direction as the turning direction of the steering shaft, thereby generating the steering assist torque. The electric power steering system s provided with an electronic control unit (ECU) to control this electric motor.
A conventional electric power steering system is disclosed in Japanese Patent Application Publication 2013-060119, corresponding to US Patent Application Publication 2013/062137. In this patent publication, an electric power steering system comprising an electric motor and an electronic control unit is described. Moreover, the electric motor is housed in a motor housing which has a cylindrical portion made of aluminum alloy etc. The electronic control unit is housed in an ECU housing which is placed on the opposite side to an output shaft in an axial direction of the motor housing. The electronic control unit housed in the ECU housing is equipped with a power conversion circuit having MOSFET which controls driving of the electric motor and a control circuit for controlling MOSFET, and the output terminal of MOSFET and the input terminal of the electric motor are electrically connected through a bus bar.
Moreover, the electronic control unit housed in the ECU housing is supplied with an electric power from the power source through an electrical connector assembly made of a synthetic resin, and is supplied with detection signals of a driving state, etc. from detection sensors. The electrical connector assembly is connected to the electric control unit by insertion into an insertion hole formed in the ECU housing, and is fixed on the outside surface of the ECU housing by fixing bolts.